Magnetron sputtering, which is also called physical vapour deposition, is a method which widely used for depositing metal layers and relevant materials during manufacturing integrated circuits.
FIG. 8 shows a typical magnetron sputtering apparatus, wherein a high vacuum process chamber is defined inside a chamber body 9′, a target material 10′ to be sputtered is provided on the top of the chamber body 9′, a top lid 11′ is provided above the target material 10′, deionized water 12′ is full filled between the top lid 11′ and the target material 10′, an electrostatic chuck which is used for holding a wafer 7′ is provided in the high vacuum process chamber, a pumping chamber is communicated with the bottom of the high vacuum process chamber.
In order to improve sputtering efficiency, magnetron 2′ is placed on the rear of the target material 10′, and includes magnets 3′ and 4′ with opposite polarities, and generates magnetic field in the portion of the chamber adjacent to the magnets 3′ and 4′ under the limitation of the track. For the self-ionized plasma (SIP) sputtering, the magnetron 2′ is small, and is a nested structure, wherein an inner track is consisted of one or more magnets and is surrounded by an outer track, the outer track is formed by a magnet which polarity is opposite to that of the magnet for forming the inner track. The magnetic field limits electrons so as to limit the motion range thereof, and extends the motion trajectory of the electrons, such that the atoms may be ionized to the greatest degree to form ions so as to significantly increase the ion concentration, and then a high density plasma region is formed in the portion of the chamber adjacent to the magnetron 2′. In order to achieve the object of uniformly sputtering, the magnetron 2′ is driven by the motor 1′ to move along a fixed trajectory around the center of the target material 10′ (which is also called scanning).
FIG. 9 shows a driving mechanism of a magnetron in the prior art, wherein, through a shaft 101′, a motor drives a gear 103′ to rotate around a gear 102′, the gear 103′ drives a gear 104′, and the gear 104′ drives a magnetron 105′ and a bob-weight 106′ to rotate, in addition, the magnetron 105′ and the bob-weight 106′ revolve around the shaft 101′, a bob-weight 107′ is used to balance the overall driving mechanism to prevent imbalance caused by torque, so as to increase the stability of transmission. The motion trajectory of the magnetron 105′ during it scans through the surface of the target material is shown in FIG. 10, a bombardment graph of the target material obtained by emulating is shown in FIG. 11, wherein the utilization ratio of the target material is about 53%, and the utilization ratio of the target material near the center thereof and at periphery thereof is low.
In summary, in the prior art, it is difficult to control the movement speed of the magnetron driven by above driving mechanism when the magnetron scans different portions of the target material, and the utilization ratio of the target material is expected to be improved.